In a perfect world, a painter would know exactly how much paint is needed for a specific job and the paint retailer would sell the exact amount needed. In the real scenario, the needed paint is estimated and then purchased in various sizes of containers, namely, quart-size, gallon-size or five-gallon size containers, which invariably means that there will be some leftover paint.
This extra paint usually ends up being stored in the original paint cans and is placed on a shelf in the basement or a garage, only to be found unusable when needed for touch-ups because during storage due to the paint hardening, drying out or otherwise deteriorating. The degradation of the paint occurs because anytime an air-curable liquid is stored in a container where air is present, the chemical process of oxidation will cause the gradual curing and subsequent degradation of the paint or liquid.
The problem of stored paint degradation due to improper storage has been recognized for some time. For example, in U.S. Pat. No. 925,447, Gunderson, discloses the use of a vapor barrier where the membrane of the vapor barrier is laid on top of the paint to create a seal inside the paint can. Another concept is disclosed in U.S. patent application Ser. No. 09/643,425, Alvarez, that uses a series of quart bottles to store leftover paint.
There remain many shortcomings in the efficacy of these methods used to store and access the leftover paint. In Gunderson, the membrane of the vapor barrier must fit perfectly along the perimeter of the container in order to create an effective seal between the paint and the surrounding air. In Alvarez, the stored paint could be potentially exposed to ambient air if the bottle is not completely full, which results in the premature degradation of the stored paint.
However, the problems associated with oxidation of materials is not only limited to paint. Air is the enemy of many substances such as wine, cooking oils, and perfumes.
Therefore, there continues to be a need for the ability to effectively remove air from a storage container in order to prevent/minimize the amount of oxidation occurring within the container.